There are a number of places throughout the world where extensive coal deposits, or like mineral deposits, are present in pitch seams. A pitch seam is a seam having a pronounced angle of inclination with respect to the horizontal. Such seams are almost impossible to mine utilizing conventional auger miners since the augers do not have sufficient conveying effect of the coal to transport the coal to the surface at necessary commercial production levels. Further, such seams are also difficult to deep mine, particularly where they have a relatively narrow "height".
According to the present invention, a method and miner are provided for the high production mining of coal, or like mineral deposits, from pitch seams. The invention is applicable to virtually any pitch seam wherein the angle of inclination is between about 15.degree.-80.degree. from the horizontal. The invention is best suited for seams having a height of about 4 feet or more, and having a substantial depth. Utilizing the invention a minimum production of 25 tons per hour can be achieved, and productions as high as 250 tons per hour are possible.
According to one aspect of the present invention, there is provided a method of mining coal from a pitch seam having an angle of between about 15.degree.-80.degree. from the horizontal utilizing a cutter and conveyor, comprising the steps of: Introducing the cutter into the seam so that it follows the angle of inclination of the seam. Powering the cutter from the mouth of the seam, so that the cutter effects cutting of coal in the seam. Substantially immediately after cutting of coal with the cutter, transporting the coal with the conveyor to a discharge point exterior of the mouth of the seam. And, continually advancing the cutter and lengths of conveyor into the seam until the desired amount of material has been cut.
The method can be practiced where the degree of penetration into the seam is greater than the original length of the conveyor by periodically discontinuing the cutting operation, adding new length to the conveyor, and then resuming continuous penetration. Where a bucket conveyor is utilized, the method may be practiced for essentially any seam having an angle of inclination between about 15.degree.-80.degree., with production levels as high as 150 tons per hour. For moderate slopes, e.g. about 15.degree.-35.degree., a drag conveyor can be utilized with expected production levels of as much as 250 tons per hour.
Where the seam is particularly wide, after a first bore of a desired length has been made, the mining equipment can be removed and introduced into the same seam, spaced along the width thereof, to produce another bore in the same manner.
According to another aspect of the present invention, a pitch seam miner is provided. The miner comprises: A power cutting means. A powered conveying means. The conveying means powered separately and distinct from the cutting means. Means for introducing the cutting means into a seam to be mined, at essentially any angle of between about 15.degree.-80.degree. from horizontal. And, means for operatively interconnecting the cutting and conveying means so that the conveying means operatively follows the cutting means and conveys cut material from the interior of the seam to the mouth of the seam.
The power drive for the cutting means preferably comprises a pair of spaced power transmission shafts extending from a power source at the seam mouth to the actual cuttinq heads. The conveyor means preferably comprises a bucket conveyor, drag flight conveyor, or the like supported by the shafts utilizing sprockets and/or guide means. A pair of spiral flight conveyors are also preferably associated with the shaft to move the cut material to the center of the seam, to be picked up by the buckets, or moved by the drag flights.
According to yet another aspect of the present invention, a pitch seam miner is provided comprising: A powered cutting means, including at least one cutting head and power transmission means extending from said cutting head to a power source mounted at the mouth of the seam. A powered conveying means comprising a pair of endless chain loops with a plurality of conveying elements operatively extending between the chain loops. And, means for operatively interconnecting the cutting and conveying means so that the conveying means follows the cutting means and conveys cut material from the interior seam to the mouth of the seam.
It is the primary object of the present invention to provide an effective method and apparatus for pitch seam mining. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.